Method of bonding a window to the window opening in a vehicle

ABSTRACT

THIS INVENTION RELATES TO A METHOD AND MEANS FOR BONDING WINDOWS INTO AUTOMOBILE BODIES. A BONDING STRIP COMPRISING A CURABLE SYNTHETIC POLYMERIC MATERIAL HAVING AN ELECTRICAL CONDUCTOR RUNNING THERETHROUGH IS USED.

April 6, 1971 A. D. ROSE 3,574,024

METHOD OF BONDINGQA wmnow TO THE wnmow OPENING IN A vmucms Filed Feb. 4,1969 2 Sheets-Sheet 1 I nventor 1 7/? Vase Attorney;

April 6, 1971 Ab. ROSE 3,574,024

METHOD OF BONDING A WINDOW TO THE WINDOW OPENING IN A VEHICLE Filed Feb.4, 1969 2 Sheets-Sheet 2 70(PLAST/CS) Ila r, 1' 7, fur

F/BPE) 5 29: (W/PE) I nventor fl/an fl fi e B A llorneys United StatesPatent US. Cl. 156-108 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to a method and means for bonding windows into automobilebodies. A bonding strip comprising a curable synthetic polymericmaterial having an electrical conductor running therethrough is used.

This application is a continuation-in-part of my application, Ser. No.531,599 filed Mar. 3, 1966 which is a continuation-impart of myapplication Ser. No. 359,097 filed Apr. 13, 1964, both of which are nowabandoned.

This invention relates to a method of and means for glazing or bondingWindshields or other transparent windows (hereinafter referred to aswindows) to apertures in the bodies of vehicles such as motor vehiclesor parts thereof and the term bonding is used herein to describe suchglazing.

In the case of a motor vehicle it has been proposed to secure thewindshield or rear window in the vehicle by applying a preformed moldedsection of elastically deformable material such as rubber to theboundary of a sheet of glass, and positioning the sheet in the aperturein the frame for the windshield or window. The molded sectioncustomarily used is relatively expensive, and there is diflicultysometimes in accurately positioning the sheet of glass in the frame.When glass is inserted, it is often damaged during fitting owing to thisdifliculty particularly when laminated glass is used, and, also, sealingin a waterproof fashion is diflicult to obtain, particularly whentoughened glass is used, owing to the wide tolerances required in themanufacture of toughened glass and the apertures in vehicles.

It has also been proposed to extrude a mixture of polysulphide rubberand curing agents onto the boundary of a sheet of glass which is thenpressed home into an aperture in the frame of a motor vehicle for awindshield or rear window; the rubber cures and secures the sheet isposition in said aperture. When the polysulphide rubber mixture is used,difliculties are encountered owing to the short pot life and workingtime of the mixture. The equipment for metering and mixing the rubberand the curing agents is expensive and complicated. The mixture is dirtyto use and causes considerable expenditure on cleaning up processes.

A primary object of the present invention is to provide for bonding awindow in a vehicle body in a relatively inexpensive, simple manner withminimal wastage of materials and to do so without restriction inavailable working time to provide a bonding which is watertight and hassuflicient resilience to withstand the stresses encountered when thevehicle is in use even at low temperatures.

The invention provides a method of securing a window in a vehicle bodydesigned so that peripheral surface portions of the window may overlieflange portions of the body which surround an aperture in the body.Initially, there is placed either on the peripheral surface portions ofthe window parallel to the edge of the window, or on the flange portionsof the body, a strip of tacky, deformable essentially non-resilientmaterial which is heat cutable to a resilient state and comprisessynthetic polymeric material curable to an elastomeric state having aresistive conductor of electricity extending lengthwise through it. Thewindow is then located with its peripheral surface portions overlyingthe flange portions and pressure is exerted to squeeze the strip betweenthe peripheral portions of the window and the flange portions whilst thestrip is soft so that the strip is deformed and fills the gap betweenthe window and the flange portions. The conductor is connected with asource of electricity and an electric current is passed along theconductor to heat the conductor whereby to cause curing of the materialof the strip to a resilient state in which it forms a tough resilientand waterproof bond between the window and the flange.

Preferably, the material of the strip is slightly adhesive in order toassist in its ready application to the window or part or frame. Thedegree of softness can vary but it is preferably such that the pressureexerted to deform the strip is only light for example, that achieved bylight hand pressure.

-In some instances it may be desirable to apply a primer to each of thewindow and flange prior to placement of the strip and location of thewindow. While this applica tion of primer is not an essential step inthe method, use of a suitable primer generally results in very high bondstrengths being obtained between the strip and the window on the onehand, and the strip and the flange or flange portions on the other, thusproviding the vehicle with a desirable safety feature. A solution ofA1020 silane (supplied by Union Carbide) black finishing grade paintbased on high viscosity chlorinated rubber, phenolic resin andepoxidized oil has been found particularly effective as a primer forapplication to painted steel flanges and a solution of Y4310 Silicone(supplied by Union Carbide) has been found particularly effective as aprimer for application to glass windows.

Preferably the strip is stored on a reel, and, it is also preferable,prior to being placed on the window or flange the strip is heated, forexample, by passing electric current along the wire, to remove anycrystallization which may have occurred in the strip.

When the strip is placed on the window or flange, it is preferred tohave it extend entirely around the aperture and have opposed endportions crossed over each other prior to passage of the electriccurrent.

Strips which may be used in a method according to the invention arethose which are heat curable to a resilient state and which in theiruncured state have sufficient surface tackiness to remain in allottedposition while the window is located and sufficient softness to allowbedding of the strip by light pressure as above referred to, togetherwith absence of recovery when the light pressure is removed, and thatafter heating display strong adhesion to the window and flange whiledeveloping suflicient resil ience to withstand vibrations of the windowand flange when the vehicle is used.

The preferred material for use in the strip comprises basically acurable polymeric material, more specifically a curable elastomer, whichin its uncured state melts to a pourable fluid when heated to atemperature of not more than 60 C. Suitable polymers for use includevarious elastomers, or curable elastomers, such asbutadiene-acrylonitrile copolymers and chloroprene polymers, for example, those known as neoprene PB and neoprene FC each of which is astabilized low molecular Weight chloroprene polymer. Neoprene FBcrystallizes at a medium rate and neoprene FC crystallizes at a fastrate, and each has a specific gravity of 1.23 at 25 C. Both thesematerials are low viscosity polymers which are soft, crystalline solidsat room temperature. They have non-shrink and non-slump properties. Weprefer to employ neoprene PB and to use this polymeric material inquantities greater than about 40% by weight of the material of thestrip, more preferably in quantities of about 40% to 45% by weight ofthe material of the strip. The quantity of the polymeric material whichis used may be reduced if the material of the strip also comprises aharder curable polymeric material, for example, neoprene AC, but this isoften undesirable because a material may be produced which is too hardfor convenient use. If more than about 60% of the low molecular weightpolymer is used the material of the strip may be too soft for convenientuse.

The material of the strip preferably includes a phenolic resin whichimparts tackiness to the material of the strip when in its uncured stateand reinforces the material of the strip when the material is cured. Inthe preferred manner, the phenolic resin is liquid in its uncured stateand is of the resole type being curable when heated in the presence ofhexamine. Suitable liquid phenolic resins include those known asCellobond H832, Bakelite 14634 and Durez 11078; preferably CellobondH832 is employed which is a liquid cashew phenolic resin having aspecific gravity of 0.93. Preferably the liquid phenolic resin ispresent in the material to an extent of not more than about 7.5 parts byweight per hundred parts by weight of the synthetic polymer present,larger quantities giving materials which tend to cure too quickly forconvenient use after more than short storage periods.

The material of the strip preferably includes finely divided fillermaterial. The quantity of filler material used depends on thecharacteristics of the filler, the type and quantity of the polymericmaterial used and the properties required of the strip; preferably thefinely divided filler material comprises a mixture of carbon black,china clay, and asbestos fiber, in a ratio by weight of 2:7:2 insuflicient quantity to provide 70% to 75% by weight per 100 parts byweight of the synthetic polymer present. Preferably the material of thestrip includes curing and vulcanizing agents, for example, canarylitharge and hexamine. The material of the strip may also includeplasticizer material, for example, non-degraded heat-softened bunarubber, dioctyl sebacate, Factice, heavy petroleum distillate orchlorinated wax.

The invention provides a glazing strip for motor vehicle windowscomprising an elongated body or strip of heat curable material having asurface that is adhesive enough to stick temporarily to a window duringassembly, and a resistive electrical conductor embedded in said body soas to extend lengthwise through it. The heat curable material is capableof change between a soft and deformable uncured state (in which it issoft enough to allow a window to be bedded into its frame, with thestrip between them, by light pressure) and a resilient cured state andis further capable of bonding to a window and frame when heated andcured. The conductor in turn is such as (when the ends of a length ofstrip such as to surround a window are connected to a suitable electricsupply) to generate the heat needed to effect such bonding and to causechange from uncured to cured state of the material of the strip.

The strip can have any desired cross-section, but we prefer to employ astrip of uniform circular cross section because this reduces to aminimum the possibility of trapping air between the window and thesurface of the strip and between the flange and the surface of thestrip.

The resistive conductor preferably takes the form of a wire extendingaxially of the strip. Ends of the wire may be exposed to facilitateelectrical contact with an external source of current supply.

Under certain conditions, e.g. where the material of the strip is,before use, very soft and where the strip is liable to be subjected torough handling, there may be a risk of the conductor wire in the stripbecoming exposed and when used may contact a metallic body so as tocause a short-circuit. In order to avoid or minimize this risk the stripmay be provided with a resistive conductor in the form of a wire coveredby a flexible protective sheath of electrically insulating material. Thesheath must, of course, be made of material such that it retains itsnecessary electrically insulating and mechanical properties whensubjected to heat from the wire. To minimize its resistance to passageof heat from the wire to the material of the strip, the sheath willnormally be made as thin as possible while retaining the necessarymechanical strength. The sheath, may, for example, comprise an enamelcoating on the wire or a sleeve of woven fabric. Preferably the sheathcomprises a resin-bonded glass fiber sleeve.

Heating of the strip as a result of passing electric current along theresistive conductor of electricity along the strip gives rise to anumber of important advantages. Initial heating softens the strip andfacilitates correct bedding of the window; it is possible to arrangethat the strip be heated to an extent suflicient to initiate its curewithout subjecting the car body or the window to appreciable heating;the center part of the strip (which is the last part of the strip whichwould be cured as a result of external heating) is cured first and it ispossible to cure the strip without difficulty when required that is, ina point in time, thus enabling a simple arrangement in the productionline to be employed.

The extent of heating of the strip which is required varies to someextent in accordance with the choice of material of the strip. With theindicated preferred materials of the strip it is usually only necessaryto apply sufficient heat to the strip to initiate curing thereof, toeffect curing of the material of the strip to a cured state in which thestrip is in a resilient state in which it forms a tough resilient andwaterproof bond between the window and the flange which is sufiicientlystrong to enable the vehicle to be driven from the production line. Withthe preferred materials, further curing of the material occurs over aperiod of days after the heating has been carried out, and the strengthof the bond between the Window and flange increases; completion of thecure occurring gradually over a period of days after the heating,

Embodiments of the invention are now described by way of example only inconnection with the fitting of a windshield to a motor vehicle and withreference to the accompanying drawings in which:

FIG. 1 is a front elevation of the windshield;

FIG. 2 is a cross-section of part of the windshield drawn to a largerscale than FIG. 1;

FIG. 3 is a longitudinal section of a modified piece of strip accordingto the invention; and

FIG. 4 is a cross-section of the strip of FIG. 3.

A heat curable material consisting of-- Material: Parts by wt. A lowmolecular weight chloroprene polymer (neoprene FB) 75 An aldehyde amineaccelerator (Du Pont accelerator 808) 1.5 An antioxidant (octamine) 1.0Liquid cashew phenolic resin (Cellobond H832) 10 Hexamine 2 Benzoic acid0.5 Non-degraded heat-softened buna rubber 20 Canary litharge 20 Carbonblack 1- 10 China clay 35 Asbestos fiber 10 is first mixed in a cooledheavy duty mixer and is then extruded onto 0.020 inch oxidized Eurekawire to form a strip 10 with the wire 11 as a core, as shown in FIGS. 1and 2. The material of the strip is soft, tacky, deformable andnon-resilient at this time, and the strip 10 is preformed of thenecessary length to extend around a motor vehicle window of givendimensions, the material at the ends of the strip being removed toexpose the ends of said wire.

A primer solution A was made up according to the following formulation.

Material: Parts by wt.

Silicone Y43l0 solution (a solids solution of silicone material suppliedby Union Carbide) 50 Toluene 40 n-Butanol 5 Butyl Cellosolve 5 Primersolution A is applied with a brush to peripheral surface portions of awindshield 12 and allowed to dry.

A primer solution B was made up according to the following formulation:

Material: Parts by wt.

Black finishing grade paint based on high viscosity chlorinated rubber(34% solids) 255 Acetone 309 Phenolic resin, e.g. Bakelite Resin 14634144 Silane, e.g. A1020 supplied by Union Carbide 21.6 Epoxidized soybean oil.

Primer solution B was applied with a brush to the boundary 15 of anaperture 13 in a vehicle body, and allowed to dry.

The strip is stored on a reel in a refrigerated cabinet maintained atabout 14 F. Immediately before removal from its reel the ends of thestrip are connected with a source of electricity and a current passed at2 volts per lineal foot for about 30 secs. to preheat the strip. Afterthe preheating step the strip is applied to the peripheral surfaceportions of the windshield parallel to the edge of the windshield 12which is then located in the aperture 13 for the windshield 12 in thevehicle frame 14, with said strip 10 abuttin against the boundary 15 ofthe aperture 13. The ends of the strip 10 are crossed over one anotheras shown in FIG. 1 but are separated by a leaf insulator 18 to preventshorting during passage of an electric current through the wire 11. Theends of the wire 11 are then connected to a source of electricity at 2volts per lineal foot for about 6 /2 minutes. The strip is allowed tosoften for the first 1 /2 minutes passage of the current, and then thewindshield is pressed into position by light hand pressure, so as tosqueeze the strip between the glass and the flange and deform it intoconformity with the surface configuration of the glass and flange.During the last 5 minutes passage of the current, the wire heats thestrip sufiiciently to cause cure of the material of the strip to aresilient state so as to bond the screen firmly to the metal, andprovide a watertight seal between the glass and the metal, havingsufficient resilience to withstand the stresses encountered when thevehicle is in use. The crossed-over ends of the strip 10 are then eithercut off or are inserted into the molding 16 which is applied afterbonding. During the days immediately after passage of the electriccurrent through the wire curing of the material of the strip continuesuntil after a few days the cure is considered complete.

If desired, spacers 17 of, for example, rubber or magnetized materialmay be located around the aperture 13 to retain the windshield 12 inposition in the frame 14 during the location of the windshield andpassage of the electric current. The spacers 17 may subsequently be leftin position or removed.

An advantage of the invention is that the sealing strip is easy tohandle, may be used on a mass production basis, does not involve mixingat the site of the vehicle, or require expensive mixing and meteringequipment, is easily stored and may be used for the method of theinvention in relatively simple manner, resulting in a saving in the costof sealing Windshields in motor vehicles.

Where it is necessary to remove a broken windshield the resistance wiremay, if sufficiently strong, be used as a cutter to cut half of thecircumference of the strip in the manner of a cheese cutter.

FIGS. 3 and 4 show a modified form of strip 10. In

making this modified strip, a material of the same composition as usedfor the strip hereinbefore described with reference to FIGS. 1 and 2 isas before mixed in a cooled heavy duty mixer and is then extruded onto awire 11 covered by a resin-bonded glass-fiber sheath 11a to form,

a strip 10 of about inch diameter with the sheathed wire as a core. Thewire may suitably be made of a 90% copper 10% nickel alloy and have adiameter of 0.024 inch (23 S.W.O.), a specific gravity of 8.95, anominal resistivity of 14.1 microhm centimeters, a resistance of 0.440ohm per yard and melting point of 1100 C. The strip 10 is preformed ofthe necessary length to extend around a motor vehicle window of givendimensions, the material and sheath at the ends of the strip beingremoved to expose the ends of said wire.

The strip is packaged on a round plastics reel to facilitate easy usage.Just before use, before the strip is removed from the reel, the ends ofthe strip are connected with a source of electricity and a currentpassed at 2 volts per linear foot for about 30 seconds to preheat thestrip.

After ensuring that the peripheral surface portions of the windshield 12and of the painted metal aperture 13 for the windshield in the vehicleframe 14 are clean, a thin coat of primer solution A is applied to theperipheral surface portions of the windshield and a thin coat of primersolution B is applied to the frame either by a brush or by a felt padwhich gauges the width of the primer application. The primer drieswithin one minute. The strip 10 is then placed upon the peripheralsurface portions of the windshield 12 and, owing to the fact that thestrip has a tacky or sticky surface, adheres thereto. The strip isarranged to extend all the way round the margin of the windshield andthe two ends of the strip are crossed over. The windshield 12 is thenlifted by means of two rubber sucker grip holders affixed thereto andplaced into the aperture 13. It is held in place at this stage solely byresting the windshield on the margin 15 of the aperture or, if desired,on rubber spacers 17 which hold the windshield centrally in position.The two ends of the wire 11 are then connected to a low voltage sourceof electricity, usually of the order of two volts per lineal foot ofstrip. Upon switching on the current supply the strip quickly heats andsoftens (in about 1 minute). After softening, the windshield is readilybedded into the aperture by hand pressure, thus squeezing the stripbetween the margin of the windshield and the aperture margin 13 (whichlatter is constituted by the pinch weld flange of the aperture), so asto deform the strip and effect a bond. After a further five minutes ofheating, the electrical input is switched off, since the heat hasinitiated a curing process within the strip and the strength of adhesionis sufiicient to allow the vehicle to be driven on the road. The marginof the windshield, which shows the strip, is then covered by the revealmolding 16 which is fixed into clips so that the joint or bond is notvisible. The crossed-over ends of the strip are either cut off beforeinserting the reveal molding or concealed behind the molding. Cure ofthe material of the strip continues during the ensuing days while thevehicle is subject to ambient temperature conditions and the material isthus permanently cured to a resilient state and bonds the windshieldfirmly to the aperture margin, providing also a watertight seal betweenthe windshield and the aperture margin, and having sufiicient resilienceto withstand the stresses encountered when the posed relationshipbetween a peripheral face surface portion of the window and the flangeportion of the body, the material of said strip being heat curable to aresilient state and comprising synthetic polymeric material curable toan elastomeric state, the said strip having a resistive conductor ofelectricity extending therethrough, and, while essentially maintainingsaid positioning,

(b) applying pressure to squeeze the strip between the peripheral facesurface portions of the window and the flange portions whereby the stripis deformed and fills in therebetween, and

(c) passing an electric current along the conductor to heat theconductor causing curing of the material of the strip to a resilientstate in which it forms a tough, resilient and waterproof bond betweenthe window and the flange.

2. A method according to claim 1 wherein the material of the stripcomprises a synthetic polymeric material which in its cured state iselastomeric and which in its uncured state melts to a pourable fluidwhen heated to a temperature of not more than 60 C.

3. A method according to claim 2 wherein the synthetic polymericmaterial is a stabilized low molecular weight chloroprene polymer.

4. A method according to claim 3 wherein the synthetic polymericmaterial provides greater than about 40% by weight of the material ofthe strip.

5. A method according to claim 2 wherein the material of the stripincludes a phenolic resin which is liquid in its uncured state.

6. A method according to claim 5 wherein the phenolic resin is presentin the material to an extent of up to about 7.5 parts by weight perhundred parts by weight of synthetic polymeric material.

7. A method according to claim 2 wherein the material of the stripincludes a plasticizer.

8. A method according to claim 7 wherein the plasticizers isnon-degraded heat softened butadiene rubber.

9. A method according to claim 1 wherein the strip extends entirelyaround the aperture, and end portions of the strip are crossed over eachother prior to passage of the electric current.

10. A method according to claim 1 wherein prior to placement of thewindow a primer solution is applied to the flange and allowed to dry.

References Cited UNITED STATES PATENTS 3,155,204 11/1964 Campbell et al156295X 3,241,277 3/1966 Coppock 156-295X 2,633,443 3/1953 Langer156-275 2,662,045 12/1953 Baggott 156275 2,952,578 9/1960 Carlson 1562753,047,703 7/1962 Asre 156---275 CARL D. QUARFORTH, Primary Examiner S.J. LECHERT, JR., Assistant Examiner US. Cl. X.R.

